For policy-specific tests, use the version before the policy was
introduced. Otherwise, use 3.5 where possible.
Also, remove `cmake_minimum_required()` and `project()` calls from
individual cases where they are handled by `CMakeLists.txt`.
Newer versions of SWIG drop support for some target languages, and some
forks of SWIG (such as for Fortran and MATLAB) aren't supported by the
mainline version of SWIG.
Swig versions as old as 1.3.6 (circa 2001) and possibly older use the
same format for listing available wrappers "%-15s - Generate %s
wrappers", so component detection should be quite reliable.
